CN109037709A - A kind of elctro-catalyst nickel, cobalt, the preparation method of phosphor codoping carbon material and its application in zinc-air battery - Google Patents

Abstract

The invention discloses a preparation method of an electrocatalyst nickel, cobalt and phosphorus co-doped carbon material and its application in a zinc-air battery, belonging to the technical field of zinc-air battery catalysts. The main points of the technical scheme of the present invention are: after mixing the alcoholic solution of cobalt nitrate and the alcoholic solution of 2-methylimidazole, leave it to stand at room temperature to react and synthesize the polyhedral ZIF-67 precursor, and then mix the ZIF-67 precursor and the nickel source in alcohol The solvent is heated to reflux in a water bath to obtain a hollow polyhedral nanocage product, and then the obtained product and a phosphorus source are heated to reflux in a water bath to react to obtain a target product. The introduction of nickel into the electrocatalyst of the present invention enhances the catalytic activity of the composite material through the synergy between different components, and the introduction of the heteroatom phosphorus effectively optimizes the electronic structure of the material and improves the electrocatalytic performance. The catalyst and the preparation method of the invention have broad application prospects in zinc-air battery catalysts.

Description

A preparation method of electrocatalyst nickel, cobalt, phosphorus co-doped carbon material and its application in zinc- Applications in Air Batteries

technical field

The invention belongs to the technical field of zinc-air battery catalysts, and in particular relates to a preparation method of an electrocatalyst nickel, cobalt and phosphorus co-doped carbon material and its application in zinc-air batteries.

Background technique

Zinc-air battery is a kind of metal-air battery, and its invention has a history of hundreds of years. The battery generates electricity through the oxidation of zinc in the air. It is recognized as an excellent energy storage material because of its large capacity, high energy, stable working voltage, long service life, stable performance, non-toxic and harmless, safe and reliable, no explosion hazard, rich resources, and low cost. Become the most promising new energy battery for the next generation.

Zinc-air battery, also known as zinc-oxygen battery, is a primary battery that uses activated carbon to absorb oxygen or pure oxygen in the air as the positive electrode active material, zinc as the negative electrode, and ammonium chloride or caustic alkali solution as the electrolyte. Key components for the charge-discharge efficiency of zinc-air batteries. MOFs have the characteristics of structural diversity, high specific surface area, and rich pore structure. They are ideal precursor materials and have important applications in the fields of gas storage, gas adsorption and separation, sensors, and catalytic reactions.

Currently, noble metals and alloys such as Pt, Pt-Au, and Pt-Pd have been studied and developed as bifunctional electrocatalysts for metal-air batteries, however, the limited availability and high cost of these noble metal-based catalysts limit their use in metal-air batteries. Long-term practical applications in air batteries. Therefore, it is necessary to develop high-efficiency bifunctional electrocatalysts to improve the charge-discharge efficiency of batteries; in addition, it is urgent to find alternative materials for noble metals to reduce the cost of zinc-air battery catalysts.

Contents of the invention

The technical problem solved by the invention is to provide a method for preparing an electrocatalyst nickel, cobalt, and phosphorus co-doped carbon material, and the electrocatalyst can effectively improve the performance of the zinc-air battery as a zinc-air battery catalyst.

The present invention adopts following technical scheme for solving above-mentioned technical problem, a kind of preparation method of electrocatalyst nickel, cobalt, phosphorus co-doped carbon material is characterized in that concrete steps are:

Step S1: respectively dissolving cobalt nitrate and 2-methylimidazole in a solvent until completely dissolved, then mixing the two solutions and standing at room temperature for 18-48 hours to obtain a polyhedral ZIF-67 precursor;

Step S2: heating the polyhedral ZIF-67 precursor obtained in step S1 and the nickel source compound in a solvent in a water bath to reflux for 0.5-6 hours to obtain a hollow polyhedral nanocage structure product with wrinkles on the surface;

Step S3: adding a phosphorus source compound to the hollow polyhedral nanocage structure product with surface wrinkle obtained in step S2, ultrasonically dispersing it uniformly in a solvent, heating it in a water bath to reflux for 1-6 hours to obtain a functionalized electrocatalyst with a hollow polyhedral nanocage structure , the average particle size of the electrocatalyst is 500nm, and the shell thickness is 20-50nm;

The solvent is methanol, ethanol, ethylene glycol, glycerol or isopropanol; the nickel source compound is nickel nitrate, nickel chloride, nickel sulfate or nickel hydroxide; the phosphorus source compound is sodium dihydrogen phosphate , potassium dihydrogen phosphate or phosphorus chloride.

Further preferably, the mass ratio of the nickel source compound to the polyhedral ZIF-67 precursor described in step S2 is 1:1-4:1, and the introduction of the nickel source compound is used to induce the polyhedron to form a microstructure that is hollow inside and wrinkled on the surface; The mass ratio of the phosphorus source compound to the polyhedral ZIF-67 precursor in step S3 is 1:1-4:1.

Application of the electrocatalyst nickel, cobalt, phosphorus co-doped carbon material in the zinc-air battery according to the present invention, the electrocatalyst nickel, cobalt, phosphorus co-doped carbon material is used to catalyze the ORR and OER of the zinc-air battery reaction.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention synthesizes a nickel, cobalt, and phosphorus co-doped carbon material double-attack-energy electrocatalyst with a hollow polyhedral nanocage microstructure. The synthesis method does not require high-temperature calcination, is simple, safe, and green and economical.

2. The hollow polyhedral nano-cage material synthesized by the present invention is preferentially introduced into metal nickel, and the stronger coordination ability of nickel makes the cobalt-based precursor form a structure with a hollow interior and a wrinkled surface, effectively expanding the specific surface area; secondly, doping with heteroatom phosphorus It provides abundant catalytic active sites, optimizes and adjusts the electronic structure of the catalyst material, and is beneficial to the improvement of the catalyst performance.

3. The hollow polyhedral nanocage material synthesized by the present invention has an internal hollow surface wrinkled structure. This fine and complex structural feature endows the material with a high specific surface area, promotes the diffusion of active substances and accelerates the electrochemical reaction on the surface of the catalyst material, effectively improving the Bifunctional catalytic activity of the catalyst.

Description of drawings

Fig. 1 is the TEM figure that embodiment 1 makes catalyst;

Fig. 2 is the FESEM figure that embodiment 3 makes catalyst;

Fig. 3 is the FESEM figure that comparative example 1 makes catalyst;

Fig. 4 is the ORR polarization curve that embodiment 1 and comparative example 1, comparative example 2, comparative example 3 make catalyst;

Fig. 5 is the OER polarization curve of the catalyst prepared in Example 1 and Comparative Example 1, Comparative Example 2, and Comparative Example 3.

Detailed ways

The above-mentioned contents of the present invention are described in further detail below through the embodiments, but this should not be interpreted as the scope of the above-mentioned themes of the present invention being limited to the following embodiments, and all technologies realized based on the above-mentioned contents of the present invention all belong to the scope of the present invention.

Example 1

Step S1: Dissolve 249mg of cobalt nitrate and 328mg of 2-methylimidazole respectively in 25mL of methanol until completely dissolved, then add the cobalt nitrate solution into the 2-methylimidazole solution to form a purple mixed solution, and let it stand at room temperature for 24h , washed several times with methanol and vacuum dried to obtain a purple powder sample, namely the ZIF-67 precursor;

Step S2: disperse 40 mg of the ZIF-67 precursor obtained in step S1 and 80 mg of nickel nitrate in 25 mL of methanol, heat it in a water bath to reflux for 0.5 h after the dispersion is uniform, wash with ethanol for several times, and vacuum dry to obtain a light green solid powder;

Step S3: Add 80 mg of sodium dihydrogen phosphate to the light green solid powder obtained in step S2, disperse evenly in 25 mL of absolute ethanol by ultrasonic, then heat in a water bath to reflux for 1 h, cool to room temperature, wash with ethanol for several times, and then vacuum dry A black target product, namely a functionalized hollow polyhedral nano-cage electrocatalyst with an average particle size of 500 nm and a shell thickness of 20-50 nm, is obtained, as shown in FIG. 1 .

Electrochemical tests were performed using half-cells of the Solartron 1287 (Solartron Analytical, England) type three-electrode system. The glassy carbon electrode coated with catalyst is used as the working electrode, the counter electrode and reference electrode are carbon rod and Ag/AgCl saturated calomel electrode respectively, the electrolyte for ORR test is 0.1M KOH solution, and the electrolyte for OER test is 1M KOH solution. The preparation process of the catalyst slurry is as follows: take 5 mg of the catalyst and disperse it in 0.5 mL of ethanol, then add a proton exchange membrane (Nafion), ultrasonically disperse for about 30 min, use a micro-sampler to take 25 μL of the mixed solution and apply it on the surface of the glassy carbon electrode. It can be tested after drying under the sun, and the electrical performance test results are shown in Figures 4 and 5.

Example 2

Step S1: Dissolve 249mg of cobalt nitrate and 328mg of 2-methylimidazole respectively in 25mL of methanol until completely dissolved, then add the cobalt nitrate solution into the 2-methylimidazole solution to form a purple mixed solution and let it stand at room temperature for 18h , washed several times with methanol and vacuum dried to obtain a purple powder sample, namely the ZIF-67 precursor;

Step S2: disperse 40 mg of the ZIF-67 precursor obtained in step S1 and 40 mg of nickel chloride in 25 mL of methanol, heat it in a water bath to reflux for 3 hours after the dispersion is uniform, wash with ethanol for several times, and vacuum dry to obtain a light green solid powder;

Step S3: Add 40 mg of potassium dihydrogen phosphate to the light green solid powder obtained in step S2, disperse evenly in 25 mL of absolute ethanol by ultrasonic, then heat in a water bath to reflux for 3 h, cool to room temperature, wash with ethanol for several times, and then vacuum dry The black target product, namely functionalized electrocatalyst with hollow polyhedral nanocage structure, was obtained.

Electrochemical tests were performed using half-cells of the Solartron 1287 (Solartron Analytical, England) type three-electrode system. The glassy carbon electrode coated with catalyst is used as the working electrode, the counter electrode and reference electrode are carbon rod and Ag/AgCl saturated calomel electrode respectively, the electrolyte for ORR test is 0.1M KOH solution, and the electrolyte for OER test is 1M KOH solution. The preparation process of the catalyst slurry is as follows: take 5 mg of the catalyst and disperse it in 0.5 mL of ethanol, then add a proton exchange membrane (Nafion), ultrasonically disperse for about 30 min, use a micro-sampler to take 25 μL of the mixed solution and apply it on the surface of the glassy carbon electrode. It can be tested after drying under the sun, and the electrical performance test results are shown in Figures 4 and 5.

Example 3

Step S1: Dissolve 249mg of cobalt nitrate and 328mg of 2-methylimidazole respectively in 25mL of methanol until completely dissolved, then add the cobalt nitrate solution into the 2-methylimidazole solution to form a purple mixed solution, and let it stand at room temperature for 48h , washed several times with methanol and vacuum dried to obtain a purple powder sample, namely the ZIF-67 precursor;

Step S2: disperse 40 mg of the ZIF-67 precursor obtained in step S1 and 40 mg of nickel hydroxide in 25 mL of methanol, heat it in a water bath to reflux for 3 hours after the dispersion is uniform, wash with ethanol for several times, and vacuum dry to obtain a light green solid powder;

Step S3: Add 40 mg of sodium dihydrogen phosphate to the light green solid powder obtained in step S2, disperse evenly in 25 mL of absolute ethanol by ultrasonic, then heat in a water bath to reflux for 3 h, cool to room temperature, wash with ethanol for several times, and then vacuum dry The black target product, that is, the electrocatalyst with functionalized hollow polyhedral nanocage structure, is obtained, as shown in Figure 2.

Electrochemical tests were performed using half-cells of the Solartron 1287 (Solartron Analytical, England) type three-electrode system. The glassy carbon electrode coated with catalyst is used as the working electrode, the counter electrode and reference electrode are carbon rod and Ag/AgCl saturated calomel electrode respectively, the electrolyte for ORR test is 0.1M KOH solution, and the electrolyte for OER test is 1M KOH solution. The preparation process of the catalyst slurry is as follows: take 5 mg of the catalyst and disperse it in 0.5 mL of ethanol, then add a proton exchange membrane (Nafion), ultrasonically disperse for about 30 min, use a micro-sampler to take 25 μL of the mixed solution and apply it on the surface of the glassy carbon electrode. It can be tested after drying under the sun, and the electrical performance test results are shown in Figures 4 and 5.

Comparative example 1

Step S1: Dissolve 249mg of cobalt nitrate and 328mg of 2-methylimidazole respectively in 25mL of methanol until completely dissolved, then add the cobalt nitrate solution into the 2-methylimidazole solution to form a purple mixed solution, and let it stand at room temperature for 24h , washed several times with methanol and vacuum dried to obtain a purple powder sample, namely the ZIF-67 precursor;

Step S2: Disperse 40 mg of the ZIF-67 precursor obtained in step S1 and 200 mg of nickel nitrate in 25 mL of methanol, heat it in a water bath to reflux for 0.5 h after the dispersion is uniform, wash with ethanol for several times, and vacuum dry to obtain a light green solid powder;

Step S3: Add 80 mg of sodium dihydrogen phosphate to the light green solid powder obtained in step S2, disperse evenly in 25 mL of absolute ethanol by ultrasonic, then heat in a water bath to reflux for 1 h, cool to room temperature, wash with ethanol for several times, and then vacuum dry The black target catalyst was obtained, and the morphology of the catalyst was not uniform, and the surface had no wrinkles, as shown in FIG. 3 .

Electrochemical tests were performed using half-cells of the Solartron 1287 (Solartron Analytical, England) type three-electrode system. The glassy carbon electrode coated with catalyst is used as the working electrode, the counter electrode and reference electrode are carbon rod and Ag/AgCl saturated calomel electrode respectively, the electrolyte for ORR test is 0.1M KOH solution, and the electrolyte for OER test is 1M KOH solution. The preparation process of the catalyst slurry is as follows: take 5 mg of the catalyst and disperse it in 0.5 mL of ethanol, then add a proton exchange membrane (Nafion), ultrasonically disperse for about 30 min, use a micro-sampler to take 25 μL of the mixed solution and apply it on the surface of the glassy carbon electrode. It can be tested after drying under the sun, and the electrical performance test results are shown in Figures 4 and 5.

Comparative example 2

Step S1: Dissolve 249mg of cobalt nitrate and 328mg of 2-methylimidazole respectively in 25mL of methanol until completely dissolved, then add the cobalt nitrate solution into the 2-methylimidazole solution to form a purple mixed solution, and let it stand at room temperature for 24h , washed several times with methanol and vacuum dried to obtain a purple powder sample, namely the ZIF-67 precursor;

Step S2: Add 80 mg of sodium dihydrogen phosphate to 40 mg of the ZIF-67 precursor obtained in step S1, ultrasonically disperse it in 25 mL of absolute ethanol, heat it in a water bath to reflux for 1 h, cool it to room temperature, and wash it several times with ethanol centrifugation Vacuum drying gave the black target catalyst.

Electrochemical tests were performed using half-cells of the Solartron 1287 (Solartron Analytical, England) type three-electrode system. The glassy carbon electrode coated with catalyst is used as the working electrode, the counter electrode and reference electrode are carbon rod and Ag/AgCl saturated calomel electrode respectively, the electrolyte for ORR test is 0.1M KOH solution, and the electrolyte for OER test is 1M KOH solution. The preparation process of the catalyst slurry is as follows: take 5 mg of the catalyst and disperse it in 0.5 mL of ethanol, then add a proton exchange membrane (Nafion), ultrasonically disperse for about 30 min, use a micro-sampler to take 25 μL of the mixed solution and apply it on the surface of the glassy carbon electrode. It can be tested after drying under the sun, and the electrical performance test results are shown in Figures 4 and 5.

Comparative example 3

Step S1: Dissolve 249mg of cobalt nitrate and 328mg of 2-methylimidazole respectively in 25mL of methanol until completely dissolved, then add the cobalt nitrate solution into the 2-methylimidazole solution to form a purple mixed solution, and let it stand at room temperature for 24h , washed several times with methanol and vacuum dried to obtain a purple powder sample, namely the ZIF-67 precursor;

Step S2: disperse 40 mg of the ZIF-67 precursor obtained in step S1 and 200 mg of nickel nitrate in 25 mL of methanol, heat it in a water bath to reflux for 0.5 h after the dispersion is uniform, wash with ethanol for several times, and vacuum dry to obtain a light green solid powder catalyst .

Electrochemical tests were performed using half-cells of the Solartron 1287 (Solartron Analytical, England) type three-electrode system. The glassy carbon electrode coated with catalyst is used as the working electrode, the counter electrode and reference electrode are carbon rod and Ag/AgCl saturated calomel electrode respectively, the electrolyte for ORR test is 0.1M KOH solution, and the electrolyte for OER test is 1M KOH solution. The preparation process of the catalyst slurry is as follows: take 5 mg of the catalyst and disperse it in 0.5 mL of ethanol, then add a proton exchange membrane (Nafion), ultrasonically disperse for about 30 min, use a micro-sampler to take 25 μL of the mixed solution and apply it on the surface of the glassy carbon electrode. It can be tested after drying under the sun, and the electrical performance test results are shown in Figures 4 and 5.

The nickel, cobalt, and phosphorus co-doped carbon material electrocatalysts prepared by the present invention all have good catalytic activity to ORR and OER. It can be seen from comprehensive examples 1 and comparative examples 1-3 that the introduction of nickel is due to its strong coordination The potential force makes the cobalt-based precursor form a structure with a hollow interior and a wrinkled surface, so that the catalyst material has a large specific surface area, and the activity of the catalyst is improved through the synergistic effect between different components. performance, so that the catalyst is expected to become a zinc-air battery catalyst with broad application prospects.

The above embodiments have described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What are described in the above embodiments and description are only to illustrate the principles of the present invention. Without departing from the scope of the principle of the present invention, there will be various changes and improvements in the present invention, and these changes and improvements all fall within the protection scope of the present invention.

Claims (3)

1. a preparation method of electrocatalyst nickel, cobalt, phosphorus co-doped carbon material, is characterized in that concrete steps are: Step S1: respectively dissolving cobalt nitrate and 2-methylimidazole in a solvent until completely dissolved, then mixing the two solutions and standing at room temperature for 18-48 hours to obtain a polyhedral ZIF-67 precursor; Step S2: heating the polyhedral ZIF-67 precursor obtained in step S1 and the nickel source compound in a solvent in a water bath to reflux for 0.5-6 hours to obtain a hollow polyhedral nanocage structure product with wrinkles on the surface; Step S3: adding a phosphorus source compound to the hollow polyhedral nanocage structure product with surface wrinkle obtained in step S2, ultrasonically dispersing it uniformly in a solvent, heating it in a water bath to reflux for 1-6 hours to obtain a functionalized electrocatalyst with a hollow polyhedral nanocage structure , the average particle size of the electrocatalyst is 500nm, and the shell thickness is 20-50nm; The solvent is methanol, ethanol, ethylene glycol, glycerol or isopropanol; the nickel source compound is nickel nitrate, nickel chloride, nickel sulfate or nickel hydroxide; the phosphorus source compound is sodium dihydrogen phosphate , potassium dihydrogen phosphate or phosphorus chloride. 2. electrocatalyst nickel according to claim 1, cobalt, the preparation method of phosphorus co-doped carbon material, it is characterized in that: the mass ratio of nickel source compound described in step S2 and polyhedral ZIF-67 precursor is 1: 1-4:1, the introduction of the nickel source compound is used to induce the microstructure of the polyhedron to form an internal hollow and surface wrinkles; the mass ratio of the phosphorus source compound to the polyhedral ZIF-67 precursor described in step S3 is 1:1-4 :1. 3. according to the application of electrocatalyst nickel, cobalt, phosphorus co-doped carbon material that the method described in any one of claim 1-2 makes in zinc-air battery, this electrocatalyst nickel, cobalt, phosphorus co-doped Heterocarbon materials are used to catalyze the ORR and OER reactions of Zn-air batteries.